Artificial tooth



June 21,1949. l I --EGGER "2,473,515,

ARTIFICIAL TOOTH.

Filed Aug. '7, 1947 /n vena/or.-

Leo/ao/d fgger 3 il @y Patented June 21, 1949 UNITED Section 1, tP-ublieLaw 690, August8,=1946 This invention relates to lartificial teeth .lasmay be used for whole -or parti-al tiental .plates as well as for bridgework.

It is an object oi this .invention to .provide san artificial toothwhose crown isrcapaioleof yielding tochewing pressuretosubstantially-the `same limited extent as do the natural teeth.

A further object of the invention to provide a composite artificialtooth whose elements @are constructed and associated .in such a :manneras to permit a limited swinging movement oi `the crown of the toothrelative to the base of the 'denture without rendering by suchconstruction the appearance of `the `tooth noticeably dierent from thatof .ordinary artificial teeth.

A further object of the invention vtis to provide an articial toothwhich combines y:limited relative movability of its cro-wn withsuiiifcient strength to take up any chewing pressure.

Still a further object of the :invention fis to pro- L vide a compositeartificial tooth having .a Icrown whose active rim or 'surfacemay .swingiorrelatively wide amounts due to a deeply located pivot for said crown.

Other objects oi the invention lappear .as `f` the description proceeds,reference had to the accompanying ldrawing which illustrates r-by way ofexample three embodiments of vthe inventvtion and in which-- Fig. 1 isva vertical section through Lan anterior tooth as secured to a baseplate;

Fig. 2 is a section along the line 12`2foi Fig. i.; Figs. 3 and 4 are,respectively, vertical isectional views of the crown of a molar toothvand y'of the vand --I2 may be polymerized tog-ether to form ya unitarybody of uniform .appearance and .the tooth may, through the intermediaryfof its part I0, be bonded or fused to the conventional :base

plate I3 of the denture also by the polymerization method, if this plate`also consists of polymeri'able material, e. g. an `acrylic resin.

The support :I I) is in the form cfa substantially conical pin which isrounded ou at rits apex to i 2 form a :rolling vsurface I4 and isprovided at its base with a marginal flange I5. The crown II has at itslower .side -a conical cavity IB whose ^apex is shaped into a rollingsurface I'I adapted to `cooperate with the rolling surface I4 of the pinI0.

The slopes of the `conical surfaces of the fpin .I0 'and the lcavity `I6are so chosen that, when the axes of these two conical :surfacescoincide, which position is .shown 1in Fig. 1, :an yannular gap ispresent between 'the .pin IIJ and the Acrown Ill which accommodates ltheintermediate layer |12 'and whose width increases -steadily from :therolling `.surfaces M, -I .'I towards the mouth vof the gap 7 Aat `thelateral 4surface of `the tooth. While `the Aarmular gap does not have tohave lthe exact vform shown in Fig. r1., -it `is essential that itsshape iris such as to .permit the crown II which bears with its rolling'surface il fdirectly, that is without an intervening elastic cushion,upon the rolling `suriace I4, 'to carry outfa apendulous movement infall 'directions during chewing. Under this `condition the crown I`-IIcan react :to the chewing .pressures in the same Imanner as would anatural tooth.

While the linear Aextent of the swing voi" the crownedge may be'variedby lengthening or short- :ching this crown edge, the tooth will in anycase he 'ableduring the `chewing Aaction to slightly give wayto the foodseized :by the teeth, and to adapt `it'sel to natural articulation. The4similarity to natural teeth becomes 'practically .perfect if thepala-tal surface, in particular that of the iront 'teeth,is shapedsoasto exactly correspond to the shape of the palatal surface of thenatural teeth.l In the :conventional artificial teeth this surfaceis-either -shortened or rarbitrarily modified. -It being, however, thetask of just the front teeth to out up the food, the heretoforeinadequate function of these articial front teeth is the main cause ofthe unpleasant vexations with which the wearer of an artificial `denturehas often to put Aup .in chewing.

In the modied'form ofthe tooth shown in Figs. 3 and 4 there are onlytw'o parts, the crown I8 and the intermediate layer 2|, which have to beAformed separately from the base plate l2'2. While there is again aconical support 23 corresponding to the lpin illifof Fig. 1, thisVsupport or pin `is an integral partfof the base plate 22, and the pinsfor all the teeth 'carried by the base plate :may be .formed with thelatter in the same molding operation. The crown I8-of non-elasticsynthetic material has again a conical cavity AI9 whose bottom Aisshaped`so as to form a bearing cup having a rolling surface 20. The cavity I9,except for the rolling surface 20, is lined with a. layer 2| of elasticsynthetic material whose cross-section, starting from the bearing cup20, increases uniformly. At its lower end the layer 2| is shaped into anannular flange 24 whose upper surface 25 rests against the bottomsurface 26 of the crown i8 and whose lower surface 2l corresponds inshape approximately to the surface 28 of the base plate 22 so that, whenthe crown together with its lining is placed upon the support 23, thesurface 28 of the base plate 22 affords a. suitable seat for the surface21 of the lining.

The plate 22 which is made of non-elastic synthetic material is shapedso as to present a support in the form of a conical pin 23 for eachtooth of the set of teeth to be carried by the plate. After the toothshown in Fig. 3 has been placed on its coordinated pin shown in Fig. 4,a permanent connection between the tooth and the base member 22, 23 isbrought about by a suitable bonding method, such as by polymerizing.

The break in the profile of the annular gap shown in Fig. l at 40 aswell as in Fig. 3 at 4| providing surfaces of small slope at the wideend of said gap improves the seat of the crown on the pin.

Fig. shows a modification of the new tooth permitting for the samedistance of the tip of the tooth from the base plate a wider swing ofsaid tip than the constructional forms shown in Figs. 1 to 4. In thelatter, the bearing point of the crown on the support or pin is situatedat vabout one-half of the total height of the tooth which arrangement isordinarily sufficient to allow for pendulous movements of proper extentof the chewing rim or surface of the tooth. The chewing rim or surfacecan swing out the wider, the deeper the bearing point of the crown islocated. Lowering this bearing point reduces the height of thesupporting pin, but it also reduces the height of the elasticintermediate layer. It is not desirable to reduce this elastic layerbelow a certain height. In order to permit a lower location of thebearing point of the crown on its support without reduction of theelastic intermediate layer, I have devised the tooth shown in Fig. 5.This tooth is composed of a support 30 which forms a bearing cup 3i opentowards the top, a crown 32 whose lower half is in the form of a conicalpin 33, and an intermediate layer 3Q. The apex of the conical pin 33 isrounded off so as to form a rolling surface 35 which cooperates with arolling surface 36 formed at the bottom of the bearing cup 3l. Theannular gap between the support 30 and the pin portion 33 of the crown32 which is occupied by the intermediate layer 34 increases in widthuniformly towards its mouth. Due to this reversed arrangement of pin andbearing cup, as compared with the arrangements shown in Figs. 1 to 4,the bearing point of the crown becomes situated much lower so that anydesired maximum amplitude of the swing of the crown may be provided forby proper dimensioning of the cushion 34.

The invention proves of particular advantage when applied to molar teethsince with these teeth it is especially important that they canyieldingly adjust themselves to such natural teeth as the wearer of thedenture may still possess.

The swing bearing of the crown prevents, particularly if the palatalsurface of the artificial teeth conforms exactly with that of thenatural teeth, any displacement of the denture and allows for acompletely natural chewing action so that the denture satisfies alldemands which may be made upon a biotechnically perfect denture.

While I have mentioned synthetic materials for the various parts of thenew teeth, I desire it to be understood that also other materials may beused, such as metal or porcelain for the support and the crown andrubber for the elastic intermediate layer. The resiliency of thisintermediate layer preferably corresponds approximately to that ofrubber for erasers.

What I claim is:

l. A composite artificial tooth -comprising a supporting member, acrown, an elastic layer interposed between said supporting member andsaid crown, a rolling surface on said supporting member, a rollingsurface on said crown, said supporting member and said crown beingshaped so that one of said two parts comprises a pin and the other abearing cup which pin and bearing cup interact at said rolling surfaces,and said supporting member and crown forming between themselves anannular gap occupied by said elastic layer.

2. A composite artificial tooth as claimed in claim l, wherein said pinis part of said supporting member and said bearing cup is part of saidcrown.

3. A composite articial tooth as claimed in claim l, wherein said pin ispart of said crown and said bearing cup part of said supporting member.

4. A composite artificial tooth comprising a supporting member, a crown,an elastic layer interposed between said supporting member and saidcrown, a rolling surface on said supporting member, a rolling surface onsaid crown, said supporting member and said crown being shaped so thatone of said two parts comprises a pin and the other a bearing cup whichpin and bearing cup interact at said rolling surfaces, said pin and saidbearing cup having each substantially conical shape with the slopes ofthe two conical surfaces being different so as to form between them anannular, towards the side wall of the tooth substantially steadilywidening, gap occupied by said elastic layer.

l5. A composite artificial tooth as claimed in claim 4, wherein the endportion of said annular gap at the wide side thereof is or reduced slopeas compared with the rest of said gap.

6. A denture comprising a base plate and at least one compositeartificial tooth, said base plate having integral therewith a pin-shapedextension for each artificial tooth carried by said plate, a rollingsurface on each said pin-shaped extension, each tooth consisting of acrown having a cavity and an elastic layer fitting into said cavity, arolling surface delimiting a portion of said cavity adapted to cooperatewith said rolling surface on the coordinated pin-shaped extension ofsaid base plate, said elastic layer fitting into said cavity and ontosaid pin-shaped extension to the exclusion of said rolling surface ofsaid cavity and said extension.

7. As an article of manufacture an artificial tooth unit consisting of acrown having a substantially conical cavity whose apex is rounded off,and an elastic layer lining the conical wall of said cavity with theexception of said rounded off part at the apex of said conical wall.

8. As an article of manufacture an artificial tooth unit consisting of anon-elastic crown having a substantially conical 'cavity whose apex isrounded off, and an elastic layer lining the conical wall of said cavitywith the exception of said rounded off part at the apex o f said conicalwall, the thickness of said layer increasing towards the open end ofsaid cavity.

9. A composite artificial tooth comprising a supporting member and acrown consisting of nonelastic polymerizable synthetic material and anintermediate layer of elastic polymerizable synthetic materialinterposed between said supporting member and said crown, a rollingsurface on said supporting member, a rolling surface on said crown, saidsupporting member and said crown being shaped so that one of said twoparts comprises a pin and the other a bearing cup which pin and bearingcup interact at said rolling surfaces, said supporting member and crownforming between themselves an annular gap occupied by said elasticlayer, and said supporting member, crown, and intermediate layer beingpolymerized together.

10. A denture comprising a base plate of polymerizable syntheticmaterial and at least one composite artiiicial tooth comprising asupporting member and a crown, both consisting of nonelasticpolymerizable synthetic material, and a layer of elastic polymerizablesynthetic material interposed between said supporting member and saidcrown, a rolling surface on said supporting member, a rolling surface onsaid crown, said carrier and said crown being shaped so that one of saidtwo parts forms a pin and the other a bearing cup which pin and bearingcup interact at said rolling surfaces, said supporting member and crownforming between themselves an annular gap which is occupied by saidelastic layer, said supporting member, crown, and intermediate layerbeing polymerized together, and said supporting member being polymerizedto said base plate.

LEOPOLD EGGER.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,460,691 Williams July 3, 19232,380,468 Sar July 31, 1945 Certificate of Correction Patent No.2,473,515 June 21, 1949 LEOPOLD EGGER It is hereby certified that errorappears in the above numbered patent requiring correction as follows:

In the heading to the printed specication, line 5, for the foreignfiling date July 7, 1946 read July 6, 1946*;

and that the said Letters Patent should be read with this correctiontherein that the same may conform to the record of the case in thePatent Office. Signed and sealed this 28th day of March, A. D. 1950.

THOMAS F. MURPHY,

Assistant ommzssz'oner of Patents.

